Field of invention relates to binders that are mass produced and capable of accommodating variable ring sizes. The binders in question are of the type that are used in schools, offices, homes and factories.
There are currently in the marketplace two types of traditional heat-sealed vinyl binders. One consists of a three-piece board construction that is welded together wherein a plastic material surrounds the three separate pieces and the hinges are formed by the plastic coverings being welded together between the spine and the front and back covers. The welded construction of this type of binder results in relatively weak hinge constructions that tend to fail with the covers pulling away from the spine. In the other traditional type, there is some connectivity or webbing taking place with the board, either the board has been slotted in the hinge areas, or it has been routed in the hinge areas, or the three pieces of board have been joined with a flexible backing. See the prior art illustrated in FIGS. 1A-D. In any case, the hinge areas are still substantially weak resulting in the covers severing from the spine. Examples of these board segmented constructions are illustrated in U.S. Pat. Nos. 5,222,825 and 5,620,207.
Another type of binder construction that has been employed is disclosed in British Patent 1,123,779. This patent discloses a binder in which a board is covered by plastic sheets that are welded to the board. However, it was found necessary to compromise the board by forming a cut-out portion at each end of a fold and thus reduces the strength of the board at the fold lines which obviously weakens the binder in these areas. There is also no teaching of providing a generally arcuate spine arrangement that is not weakened at any section thereof.
It can be appreciated that the aforementioned constructions have a number of inherent disadvantages that if overcome would be a substantial advance in the art and serve a long felt need to provide a binder with a much longer shelf life than is currently available. With the current construction the areas where the spine of the conventional binder hinges with the front and back covers have been substantially weakened by the welding in the hinge area. For example, in welding two pieces of 0.015 gauge thermoplastic material, the resultant thickness is not the expected 0.030 gauge but is approximately 0.020 gauge or less. The welding process forces the flexible plasticizers away from the welded area because pressure is used to create a bond and inevitably there is always a decrease in plasticizers and a resultant loss in dimensional stability in any welded area.
Additionally, when the binder is fully loaded with paper, there are additional stresses placed on the covers of the binder. These stresses are transferred to the area of weakness found in the hinges which further acts to rapidly deteriorate the binder thus substantially reducing its longevity.
Of primary concern is that in the conventional binder the material forming the binder has been drastically compromised by milling, routing or slotting to facilitate the formation of the hinges which brings about the weaknesses above referred to. In addition this compromising of the board strength not only increases the likelihood of hinge failure and cover separation but it can also create a wobbling effect that does not allow the binders to stand up on their own when loaded with paper.
Another disadvantage of current binder constructions that need correcting is the ability to permit the binder producer to not have to predetermine what configuration the binder construction is to be ultimately fashioned until specific orders are received. This is not possible with currently available types since the milling, routing or slotting referred to must be done before the plastic sheets forming the final binder are secured to the underlying board via the heat sealing process, and are also predetermined by the tooling used to heat seal the plastic sheets around the board. It would be a substantial advantage to have the sandwich of board and surrounding plastic sheets stacked and available to be formed into any desired configuration (i.e. round back, flat back etc.) and the instant invention would allow the configuration to be determined after the final casing has been constructed, thus reducing inventory and lead times.
Also, under current practice the final construction for the capacity of the ring metal must be selected prior to welding the film to the board since the size and shape of the binder are predetermined because of the tooling and board specifications.
It remains to mention that the current manufacturing steps being employed as disclosed in U.S. Pat. No. 5,620,207 result in protuberances that are large and unsightly if not dealt with. These are often overcome by notching the board which further weakens the binder by reducing the amount of material at critical junctures or by welding a notch to hide the protuberences which changes the dimensional stability of the plastic covering and weakens it.
It can be appreciated that it would be desirable to have a one piece uniformly strong binder in which the rigid thickness of the cover continues throughout the hinge and is unable to rip or separate. Such a binder would not compromise the board nor have relatively weak hinge lines nor create protuberances or alter the virgin raw materials in the critical failure and stress areas of the hinge. The binder should be capable of using a vinyl or other suitable plastic covering that can be welded and/or glued and/or stitched around the underlying one-piece board. It would be a substantial advance in the art if the binder would have a seamless configuration and include a creased hinge construction that is the same thickness throughout the board and thus does not define a weakened hinge area yet provides a high degree of flexibility that will vary with the number of creases formed.
Also, it would be advantageous to have a binder that is versatile, that can have either a round or a flat spine and can also be changed in size. This can be especially appreciated in manufacturing because of fewer parts, simplification in tooling, and more efficient production procedures.
There has also been a need to provide a vinyl or other plastic covering for the binder that will not delaminate or split and be able to receive a clear plastic overlay to hold information. The clear plastic overlay differs from prior art in that it can extend from the front cover to the back cover and spine without interruption and can be made flat or round after the fact. To facilitate the manufacturing of a binder that overcomes the disadvantages of the prior art the heretofore relatively archaic process used to form binders is not suitable and a new process for manufacturing binders is required.
It is also desirable to be able to provide the inner plastic covering of the binder with partial plastic sheets adhered thereto on three sides to provide pockets into which various materials can be placed.
In accordance with the present invention there is provided a seamless binder formed from a solid non-segmented piece of board with the inner and outer layers of the binder consisting of a plastic material that can be connected together in a variety of ways consisting of welding and/or stitching and/or gluing.
The novel process starts with one continuous, non-interrupted piece of board, which may be solid chipboard, paperboard, or corrugated board to save on weight. In any case, the board has not been mechanically altered with creases, scores, or routed channels. The board retains its structural stability because it is in its original state from the mill and has never been compromised.
Next a plastic skin is formed over the board on both sides. This can be done by welding two sheets of plastic together to encapsulate the one-piece board. The plastic material can, for example, consist of a vinyl such as polyvinyl chloride (PVC), a polyolefin, a polyethylene, a polypropylene or a polyvinyl acetate (PVA) or other plastics that may be secured to a board, plank, or substrate forming a unibody construction by welding and/or stitching and/or gluing.
In the preferred process embodiment prior to the welding, a thin layer of glue is spread on the board or the vinyl to make contact complete and form the one-piece design. At this point in the process, the board being used is in a flat unweakened state. The unibody design is then sequentially hydraulically creased using three moving blades, to displace a section of material to form living hinges which function like a xe2x80x9cjointxe2x80x9d or knuckle, defining the spine section of the binder between the covers where hinging and bending occurs. The thickness of the assembly is continuous across the entire binder. The unique aspect is that in the spine hinge area there is substantially 100% of the material that is throughout the cover, unlike previous binder constructions where material must be sculptured out or cut so the bending can occur. If the unibody construction is not to include gluing this step in the process would be eliminated. Also, if the plastic covers are to be stitched instead of glued the gluing step is eliminated and the stitching is added after the welding step.
The major advantage of the one-piece binder forming the instant invention is that there is no weakened, segmented board or no separate covers and spine. The covers cannot shift, loosen, rip off or pull away from the spine. The spine of the one-piece binder is formed by pressing a series of longitudinal grooves into the sandwich to create a flat or rounded spine between the front and back covers. In a preferred embodiment the inner and outer layers of the plastic materials used can be connected together by radio frequency, dielectric welding, or thermowelding at their edge portions. The solid or hollow or corrugated board can be sandwiched between plastic sheets, held with adhesive and perimeter welded, and then creased as one unit. The board does not get routed or formed prior to welding. After the creases are formed the adjacent positions of the board are bent about the creased spine section to form a binder. A ring mechanism is then suitably secured to the back cover.
In other embodiments of the present invention, the welded plastic coverings can also be glued and/or stitched to the board. Each of these configurations in conjunction with the spine construction is new and novel and is not anticipated by the prior art.
In addition to the novel process for manufacturing the novel and unique unibody binder disclosed the process can be used for forming a unique unibody binder with a fold-over flap which binder can also be converted into an easel or with an extended flap to give it a portfolio appearance.
Also, the unibody binder construction can be provided with a continuous clear vinyl overlay to form a billboard across the front cover, spine, and back cover and with pockets for inserts.